Reference
Karsten Grunewald, Jörg Scheithauer (2007): What can mountain regions in Southeast Europe learn from the Alps? Tourism vs. National Park in Bansko/ Pirin, Bulgaria – IGF-Forschungsberichte (Instituts für Interdisziplinäre Gebirgsforschung [IGF]) (Institute of Mountain Research) – 2: 295 - 302.